Karsten Sølvberg

Karsten Ludvig Sølvberg (19 January 1905 – 1976 ) was a Norwegian communist, trade unionist and agent during the Second World War.

Before the Second World War he was a trade unionist and member of the Communist Party. He was a telegraph clerk by occupation. His union was , and he edited the union's magazine .

During the occupation of Norway by Nazi Germany, the Nazis merged his union with others to form the . Sølvberg was a union secretary. He was initially a member of the resistance movement, and was arrested in October 1942 by account of "illegal activity". He had then been subject to torture. He was pressured to denounce his communist adherence, and to become a Nazi agent with the codename S 71. His agent practice was unveiled when Georg Angerer defected to Sweden. He was however acquitted of treason by Oslo City Court in 1949, when tried as a part of legal purge in Norway after World War II.